Yes manic eposides come out of the blue...I would just say that strong may not be the right word as many of my eposides have different levels...

Mine come on quickly and I cycling quickly between depression and mania...and sometimes experience both...

So there a vague answer for you...This may not be the first...we are good at hiding the good and the bad times...

I wasn't diagnosed until this year...age 36...had issues for over 20 years...never really understood...

The talking fast and some of the other items mention could be a sign of some level of mania...only a pdoc or therapist could evaluate that...so be there for him...learn what you can about bipolar...when he is ready...help him get hooked into some professional help to sort it all out...